Reduction-furnace.



G. VAN BRUNT. BEDUGTION FURNACE. APPLICATION nun I'BB.10,190B;

2 Y Patented Nov. 17,1908.

Ihventor 1 char'fesyrunt. I by Witnesses UNi En STATES PATENT OFFICE v CHARLES VAN Bun-NT, or SCHENEOTADY, New YonK, 'ASsIGriOR 'ro GENERAL nIJnc rmc COMPANY, A CORPORATION OF NEW YORK.

RnDUc'non-FUnNAcE.

Specification of Letters Patent.

Patented Nov. 1?", 19th Application filed February 10, 1908. Serial No. 415,025.

To all whom 'it may concern: I

Be it known that I, CHARLES VAN Baum,

- a citizenof the United States, residing at Schenectady, county of Schenectady, Stateof New York, have invented certain new and useful Improvements in ReductiomFurnaces, of which the following is a specification.

My invention com rises a special reduction. furnace for the re notion of metallic compounds, such as oxids, to yield reduced metals of great purity and fineness.

For some pur poses it is necessary to obtain a metal in a very fine state of division which at the same time will be exceedingly pure. In order to fulfil both these conditions the metal should be reduced from its compounds in this finely divided condition as subsequent grinding may be impossible or impracticable because, of the danger of introducing im )urities. It is vwell known that finely divi ed metals are oxidized with great ease, therefore, unusual difficulties presentthemselves in the reduction of the metal in this condition. For example, the reduction of tungstic oxid with hydrogen takes place according to the following reaction This reaction is reversible,- -therefore, great care must be used not to bring the reduced tungsten in contact with the watery vapor, which is the by-product of the reaction. I My device is designed to produce a very pure, finely divided tungsten. I accomplish this by effecting a reduction of the oxid in a current of reducing gas, such as hydrogen. The watery vapor, which results from the reaction, is swept by the moving stream of hydrogen, away from the already reduced, tungsten." The linear speed of this moving stream of hydrogen must be great enough to carry away the moisture at a rate which will. exceed the rate of diffusion of the watery vapor in the opposite direction. In this way I avoid all re-oxidation of the reduced inetallic tungsten.

As will be hereinafter described, a number of reduction chambers are connected in series,but between every two consecutive is connected a drying chamber so as to keep the concentration of the-watery vapor at a lowvalue. As only a portion of the hydrogen is oxidized in the reaction, the unused hydro gen, together with such additions as necessary to make up the losses, is retnrned to the furnace. I y

The var ous features of novelty of my in vention are pointed out in the appended claims; but a better understanding of my invehtion may be obtained from the following description taken in connection with the aocom panyi ng drawings.

Figure 1 shows a perspective view of my reducing furnace, together with a diagranrmatic representation of the system for maintaining a continuous circulation oi the hydrogen. Fig. 2 shows a longitudinal section of one of the tubular reducingchambers, and also shows a drying chamber; Fig. 3 shows a cross section 0 the reducing tube taken online 33 of Fig. 2.

As shown in Fig. 1, there are arran ed in the upper ,partof my furnace numner of parallel reduction tubes 1, supported by the framework 2. ()n the lower part of the furnace. are arranged similarly a series or" parallel absorbing chambers 13, similarly supported "by (he fran'iework The reduction chambers are connected in series with the drying chambers by means of tubes 4 in such a manner that gas entering a reduction tube willbe carried to :1 dr *ing tube, then back to a second reduction tube, then to another drying tube, and so on through the furnace. The reduction tubes and connecting tube 4.

may be made of any suitable metal, such as copper or iron. The drying tubes may be conveniently made of glass. T icy may contain any suitable drying agent, sulfuric acid. The ends of the tubular reduce tion chambers are water-cooled, as shown in the drawing. As here shown, the water enters by means of a tube 5, and after circulating through the hollow supporting frame 2 is carried away by the tube 6. The cooling arrangement is similar on both sides of the furnace.

The tubular reduction chambers are heated by means of a. traveling member 4,

which travels from one end of the furnace to the The traveling. heater be returned at the end of the run to i is initial position by disengaging it by hand from the Worm gear. This may be accomplished by pressing the spring 12, which will separate the member 13 engaging with the worm gear, and the traveling heater may then be rolled back to its original position.

The furnace is supplied with a reducing gas, as hydrogen, from the reservoir 14, which may be, for convenience, a rubber bag. It is carried by means of the tube 15 through the wash bottle 16, which may be partly filled with a washing liquid, as sul furic acid, and is carried from thence to thefirst reduction tube of the furnace. As be-v fore described the gas passes through the furnace, going alternately through a reductiontube and a drying tube, where the products of the reaction are absorbed, and finally passes out in tube 17, is passed through another Wash bottle 18, and is returned to the collectin reservoir 14 by means of a pump 19. T 0 hydrogen used up in the reaction is replaced by an additional supply of hydrogen from the reservoir 20, which is supplied from the hydrogen generator. The pressure of hydrogen in the collecting reservoir 14 is at all times indicated by a mercury gage 21. I

In order to make the zone of heating in the reduction tubes as uniform as possible, the heat is reflected downward by means of the V shaped hea't reflecting shield 22, which may be made of iron lined on its inner surface with some refractory non-conductor of heat, such as asbestos. This heat reflector 22 is connected rigidly to the traveling heater, and, therefore, moves with it across the furnace.

Having described. my apparatus, I Will proceed to explain the operation of' the fur- I nace.

The reducible oxid, as,'for example, precipitated tungstic oxid W0 of a fineness commensurate with the degree of fineness desired in the reduced metal, is placed in shallow boats, 23, such as shown in Figs. 2

and 3. These boats may be made of copper.

The boats partially filled with oxid, are inserted in the reduction tubes-'1 of the fur nace. The reduction tubes and the drying tubes are then connected in series as before described, but leaving disconnected the return tube 17 where it .joins the Wash bottle 18. The furnace is connected to the hydrogen supply system, and the flow of hydrogen is started by setting in o eration the pump 19. After all. the anhas een swept out the furnace connection is made between the tube 17 and'the wash bottle -18, thus permitting a continuous circulation'of the h drogen through the system. The flames in t e movable heater 7 in its initialposition at the extreme end of the furnace are lighted, and the chain drive 11 is set into motion. The

movable heater travels across the furnace at a very slow rate of speed, so as to complete the run in about one and one-half hours. The gas flame is so regulated as to produce a temperature in the'charge of about 600 to 800 C. \Vhen the run is completed the gas supply is cutoff, the reflector 22 is removed from the tubes. As shown in the drawing, it consists of two identical parts rigidly connected together, so as to balance one another. As here shown, the parts may be simply in terchangeable. The hydrogen current is continued in circulation for about ten to twenty minutes, or until the furnace is partly cooled off. The hydrogen supply is then cut off,

and the reduction tubes 1 are opened by re moving the stoppers 24, and the hydrogen allowed to slowly diffuse. The previous cooling of the furnace and the slow diffusion of the hydrogen are necessary, as the reduced tungsten is very apt to catch fire in the air if this precaution is not taken. The reduced metallic tungsten is now ready to be removed from the furnace.

When a very line grade of tungsten is made it is sometimes necessary to empty the reduction tubes in an atmosphere of carbon dioxid so as to avoid all possibility of reoxidation of the tungsten.

I do not desire to limit myself to the particular construction and arrangement of parts here shown, but aim in the appended claims to cover all modifications which are within the scope of my invention.

\Vhat I claim as new, and desire to secure by Letters Patent of the United States, is,-

l. The combination of a plurality of tubular envelops, means for producing a flow of reducing agent through said envelops, means for heating a zone of said envelops, and an: tomatic means for progressively advancing the zone of heating longitudinally along the said envelops.

2. The combination of a plurality of tubular envelops connected in series, means for producin a flow of reducing agent through said enve ops, means for heating a restricted zone of said envelops and automatic means for progressivel advancing the zone of heating longitu inally along the said onvelops.

3. The combination of a plurality of tubular envelops connected in series, containers, provided with a moisture absorbing agent in an intermediate relation between successive pairs of the tubular envelops, means for heating a restricted zone of said envelops,

and automatic means for progressively adongitudlnally velops, an automatic means for progressively advancing the zone of heating longicnvelops, and automatic means for progress- 1;) tudinall along the said enveiops, and means ivoly advancing the zone of heating longifor defiecting heat downward upon the tudinally along the said envelops. heated zone. In witness whereof, I have heneunto set 5. The combination of aplurality of tubumy hand this 8th day of February, 1908. lar envelopsQmeans for producing a flow of CHARLES VAN BBUNT. reducing agent through saidenveiops, meansv \Vitnesses:

for; heating a contracted zone of said en HELEN ORFOBD,

velop's, means for cooling the ends of said MARGARET E. \VOOL EY. 

